The invention relates to the manufacture of plastic shaving razor handles.
Shaving razor handles are often made of molded plastic. It is known to first mold a portion of the handle of hard plastic and to then mold elastomeric grip portions at desired locations on the hard plastic portion.
The invention features, in general, making a shaving razor handle by molding an inner core of a first plastic in opposed first mold cavities, molding an outer portion of a second plastic around the inner core in opposed second mold cavities, and molding at least one elastomeric grip portion on the outer portion at opposed third mold cavities.
Preferred embodiments of the invention may include one or more of the following features. In preferred embodiments, the first and second plastic can have the same composition and can have the same or a different color. E.g., both plastics can be of clear plastic. The inner core can be molded about an engagement member and can be moved from the first mold cavities to the second mold cavities by moving the engagement member. The inner core and additional plastic added at the second mold cavities can be moved from the second mold cavities to the third mold cavities by moving the engagement member. A plurality of inner cores of the first plastic can be simultaneously molded at first mold cavities. A plurality of outer portions of the second plastic are simultaneously molded at the second mold cavities. A plurality of elastomeric grip portions can be simultaneously molded at third mold cavities. The inner core and additional plastic can be removed from the engagement member after molding the grip portion, and a handle connection component that has a shape that is similar to the shape of the engagement member can be attached to the handle. The inner core can have a hole passing therethrough, and the additional plastic for the outer portion can be gated through the hole from a first side surface of the inner core to a second side surface of the inner core. A portion of the inner core can be supported at the first side against a mold surface while the additional plastic flows past the second side surface.
In another aspect, the invention features a shaving razor handle made by the method described.
In another aspect, the invention features apparatus for carrying out the method described.
Embodiments of the invention may include one or more of the following advantages. A thick plastic portion of a shaving razor handle can be efficiently molded in two steps by reducing the amount and thickness of plastic that is injected and cured at one time. By injecting the plastic in two steps, the formation of the part is much quicker than it would be if the entire amount of plastic were injected in a single step. Quick curing can desirably provide for maintenance of a textured surface finish that might otherwise melt to a smooth surface with dissipation of heat from a thick molded part.
Other advantages and features of the invention will be apparent from the following description of a particular embodiment thereof and from the claims.